Some boys come into a room and sit in a circle. Four girls come in and arrange themselves between 2 of the boys, that is , the 4 girls join the circle, but all sit together. If there are 2880 different circles that could be formed in this way, how many boys are there?
Suppose that there are N boys. If N boys sit in a circle, there are (N-1)!=1*2*...(N-1) possible ways to form a circle. ...
Permutations are investigated.